Teen Drug Abuse Linked to 'Impulsive' Brains

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A brain network associated with impulsivity is linked to teen
drug abuse, new research finds.

Teens with diminished activity in a
neural network in the front part of the brain are more likely
to experiment with drugs, cigarettes and alcohol in early
adolescence, the researchers found. Interestingly, this network
is not the same one that is linked to the impulsivity of teens
with attention deficit/hyperactivity disorder (ADHD). That could
mean that ADHD is not as much of a risk factor for drug abuse as
researchers have worried.

"The take-home message is that impulsivity can be decomposed,
broken down into different brain regions," study researcher Hugh
Garavan of the University of Vermont said in a statement, "and
the functioning of one region is related to ADHD symptoms, while
the functioning of other regions is related to
drug use."

Garavan and his colleagues scanned the brains of 1,896
14-year-olds as part of a large international project called
IMAGEN. Using functional magnetic resonance imaging (fMRI), they
identified parts of the brain that were linked into networks by
determining which areas became more active at the same time as
one another. During the scans, the teens did a task that involved
pressing a button and then having to keep themselves from
pressing that button at a certain cue. This task requires the
brain to inhibit behavior. [ Inside
the Brain: A Journey Through Time ]

The researchers found that a quiet orbitofrontal cortex, the part
of the brain tucked behind the eyes, was linked to more
experimentation with substances, and that the diminished activity
likely contributed to this experimentation rather than being a
cause of it.

"The differences in these networks seem to precede drug use,"
Garavan said.

Without an active orbitofrontal cortex network, the teens are
more impulsive, said study co-author Robert Whelan, also of
the University of Vermont.

When given the opportunity to smoke, drink or try drugs, the
14-year-old with a less functional impulse-regulating network
will be more likely to say, "yeah, gimme, gimme, gimme!" Garavan
said.

ADHD is also marked by poor impulse control, but the researchers
found that the poor inhibitory control in ADHD teens was
regulated by a different control network. That finding adds
nuance to concerns over the risk of drug use in ADHD
teens, the researchers report Sunday (April 29) in the
journal Nature Neuroscience. Early educational intervention can
help boost inhibitory skills, dampening impulsivity, the
researchers added.

"The efficacy of these interventions may be related to the extent
to which they engage the appropriate brain regions," the wrote.